In the world of amphibian celebrities, there's no bigger star than Kermit the Frog.

Yet back in January on the set of Disney's upcoming film "The Muppets" — the first big screen outing for Jim Henson's beloved menagerie since 1999's "Muppets in Space" — the bona fide A-lister was all hard work and self-deprecating charm. Just minutes before heading inside a Universal soundstage to film a scene in which he commends his performers on a hard day's work, he took a minute to explain to a reporter that he's found some renewed sense of inner peace, particularly when it comes to being green.

"It's easier than it used to be — I went to a being green support group and I'm much better now," Kermit said, before quickly adding one caveat, "I should say that if any of your readers turn green, they should probably see a doctor."

Opening Nov. 23, "The Muppets" posits that the longtime friends have gone their separate ways, the old theater where they famously put on their variety show fallen into disuse and extreme disrepair. While touring the building on a vacation visit to Los Angeles, brothers Gary (Jason Segel) and Walter (a new Muppet) learn of a nefarious plan on the part of the greedy Tex Richman (Chris Cooper) to demolish the property and drill for oil.

Determined to thwart his scheme, the duo — along with Gary's girlfriend Mary (Amy Adams) — seeks out Kermit and the gang and helps them plan a fundraising telethon to raise the $10 million required to buy back the historic site.

Segel, who produced the film and co-wrote the script with his "Forgetting Sarah Marshall" director Nicholas Stoller, had one word to describe his reaction to starring alongside Kermit: "awe-struck." It was the comedic actor, who has a background in puppeteering, who approached Disney with the idea of bringing the characters back to the multiplex. Their absence had been notable: The 1999 feature aside, the Muppets' heyday stretched back to the late '70s and early '80s, when the television show was a weekly fixture featuring guest stars including Liza Minnelli, Gene Kelly, Milton Berle and Alice Cooper.

When the studio sparked to the notion, Segel and Stoller recruited a friend, first-time feature filmmaker James Bobin (HBO's "Flight of the Conchords"), to direct a full-blown movie musical starring Kermit and company. All three agreed that the tone of the movie should recall Henson's patented blend of sweet-natured joviality and sophisticated silliness, eschewing the winking pop culture allusions and self-referential cynicism so common to movies and TV shows made for children these days.

"Maybe it's a generational thing," Bobin, 39, said, sitting in the empty auditorium of the Muppet theater set. "We're all kind of roughly the same age and have the same feeling about the Muppets … We're trying to be very true to the original idea of what Muppets are, their innocence and exuberance, their love of puns and fourth-wall-breaking jokes. It's like anarchic stupidity."

Introducing the new Muppet Walter became something of a daunting prospect, and one that Segel and Stoller say they didn't take lightly. The story of the film is, in many ways, the story of Walter finding his place in the world — growing up with Gary in the picturesque burg of Smalltown, USA, Walter has always realized that he's not quite like everyone else, a point underscored in a visual gag early on in which he struggles to stand as tall as his towering sibling.

Walter comes to love the Muppets because he senses that, deep down, he recognizes himself in them.

"Walter is a super fan," Segel said. "Walter's like me when I was a kid — his dream has been to meet the Muppets because they're the only people in the world he's ever seen that are like him … and the Muppets, they include everybody."

Segel, who was shuttling between shooting "The Muppets" and his CBS sitcom "How I Met Your Mother," was all smiles as he prepared for another take.

"It's really tough to be in a bad mood around the Muppets," he said. "Everyone, including the crew, when we get tired, all it takes is to see Kermit — you don't want to be a jerk in front of Kermit."